The invention relates to a method for operating presses comprising a ram and a die, such as forming processes or cutting presses, for example multiple-die presses for large workpieces, transfer presses, multi-ram transfer presses, such forming presses or cutting presses also being arranged in press lines.
Such forming presses, press lines or cutting presses essentially comprise the work steps of feeding, optionally centering, forming or cutting, and depositing the parts, with integrated transfer steps for the parts. In general, means for a transfer system are provided for transporting the parts that are formed or to be formed, or cut or to be cut, optionally via a centering system. The cooperation of these steps and systems is matched to the cycled forming strokes, or cutting strokes, of the respective forming press or cutting press. Both the cycled operating mode to be maintained, and notably the superposition of movement processes for pressing and transferring the parts to be worked, require spacing resulting in a so-called freedom of motion of the press. This necessary freedom of motion is an essential criterion for the design or configuration of presses of the type mentioned above in terms of kinematics and construction.
Given the complexity of the processes and systems of these types of presses, they are subject to increased market demands in terms of cost reductions for the press itself, and the drive trains thereof, as well as peripheral devices, and increases in the performance thereof.
It is now obvious to analyze forming presses or cutting presses, and peripheral systems, in terms of the required dimensions thereof, so as to lower costs by optimizing:                construction by way of material savings; and        process flows.        
Any increase in the performance of the drive trains, which is also required so as to boost the output of the press, in turn typically requires higher costs.
The implementation of the desired large strokes, and hence large presses, as well as powerful drives, is in contrast with necessary cost reductions, although the demand for cost reductions on the part of the market is urgent.
Considerations intended to create solutions that are less expensive or optimized in terms of output must generally abide by press technology rules, which are primarily as follows:                The overall system, as described above, is subject to physical limits, which are defined by technical functions such as        avoiding collisions of the involved transfer means, dies and workpieces,        forming forces and forming speeds, and        accelerations and speeds, and the temporal change thereof, while transporting parts between the forming stages.        The diversity of shapes, and more particularly the three-dimensional shapes of the parts, such as workpieces, the transfer thereof and the dies involved call for a high freedom of motion of the presses, as addressed above, which is typically achieved with relatively large stroke lengths of the press rams, and press frames and drive trains that are designed accordingly, in turn, result in high costs.        
So as to achieve a balanced relationship between this freedom of motion and stroke lengths, advantageous transfer means, such as so-called crossbar feeders and/or swing arms, are already used according to an internal state of the art.
The principle of the two systems involves moving a crossbar over the part to be transported so as to then hold the part itself over a vacuum suction pad attached to the crossbar during transport. The transfer units differ only with respect to the drive kinematics.
Based on the special kinematic processes for transporting the parts, such as workpieces, from one work step to another, and the pivoting thereof during the transport process, including the deformation or cutting operation, alone, these systems can be used to achieve optimized stroke lengths for the presses.
The progression of a press ram in the form of a diagram tracked by a person skilled in the art during such press processes is shown, for example, in the curve according to FIG. 1, with respect to the understanding of the prior art. The curve approximately follows a progression according to f(x)=sin x. In theory, a ram stroke of 1590 mm, a line stroke rate of 16 strokes/minute, and a forming speed of 600 mm/s at 200 mm before the lower reversal point (UU) are assumed. In practice, ram strokes up to approximately 1400 mm were carried out, with the corresponding drawbacks.
This progression of the ram curve is typical of presently known presses of the type mentioned above, which is shown, amongst other things, by the documented prior art.
The advanced prior art in question has always observed the physical rules set forth above.
The presses developed based thereon, and the processes thereof, do not reveal any potential, without further action, for solving the complex problem of how to:                further increase the output of presses on the one hand; and        lower the height, material use and costs on the other hand.        
The analysis of the prior art provided below shows only isolated improvements in this regard.
According to DE 10 2004 015 739 B4, the stated problem was already that of providing a dedicated transfer device for each of the consecutively arranged forming stages of a multi-ram transfer press, in which the orientation stations can be eliminated, and which is suitable for retrofitting older multi-ram transfer presses. To this end, the vertical movements of the crossbars of the carriages, which are arranged in pairs, are directed by a swing arm, such that the size of a pivot angle can be adjusted via a drive and a gear and bearing means.
According to DE 10 2004 030 678, the object was to achieve the most compact shape possible, so as to reduce the complexity of control of a metal-working press. However, the solution focused on the function of the associated die cushion. The pressure application that is regulated only has a marginal effect in terms of compact design for the overall press.
A review of DE 10 2005 024 822 A1 shows that this document was already directed to a simulation method for transfer presses, whereby workpiece output can be optimized, while avoiding collisions. While the simulation program associated with the press controller achieves advantageous workpiece output and allows collision-free patterns of movement, after previously calculating collision risks, the heretofore customary heights of the presses must be maintained.
Moreover, in a production line such as a press line in accordance with DE 2005 040 762, operation-related deviations of the main working directions must take place without impairment.
The work processes are coordinated with a master computer, by meaningfully linking workpiece working devices and workpiece transporting devices. Although there is positive effect in terms of optimized workpiece output, the customary heights of the presses still remain.
The problem stated in DE 10 2007 003 335 A1 was that of facilitating the programming of drive units for presses which comprise one or more servo motors and a ram, which are connected to a coupling gear. The coupling gear was provided with ratio characteristics which, in the vicinity of the bottom dead center of the ram, exhibit high dynamic rigidity. The program captures representations of the resulting movements of the ram so as to intervene in a controlling manner.
In a drive device for a multi-ram transfer press according to DE 10 2007 024 024 A1, both high pressing forces and variable ram movements are to be implemented using at least one primary drive and at least one secondary drive.
The relatively high complexity of the entire drive device for transmitting the driving energy to all stages of the multi-ram transfer press, or to all individual presses of the press line, offers no suggestions in terms of finding implementation options for reduced height.
Finally, even with a multi-point forming press for ram movement in accordance with 10 2007 026 227 A1, high pressing forces were to be implemented with the available torque of servo motors, in addition to which the driving expenditure was to be lowered using several mechanically synchronized pressure points, so as to obtain, amongst other things, a favorable spatial tilt design in two planes. The combination of crank wheels, intermediate wheels and pinion shafts, in the framework of a gear-reducing unit, which was provided as the solution, does not offer any advantages in terms of decreased height or optimized workpiece output.
Thus, after critical analytical review of the examined solutions and the rules applied, further approaches must be found for distinguishing these with respect to a new stated technical problem relating to demand for cost reduction.